Accelaration problems on take off

[dlboivin]

Strange thing is happening with my 1997 Lumina (130,000 miles on the engine). When I start the engine (3.1) it idles well and sounds good. I will drive it for about 30 seconds then it jerks or shudders slightly, and does not appear to take its gas, almost if it was being held back. If I press the gas about midway down it accelerates immediately. Once the car is warmed up it works fine. This only occurs at low speeds.

One other thing that I noticed when this occurs the oil pressure is high (on start-up) , then as the engine warms it drops, and finally drops again to about 200 PSI where it drives fine and where I experience no hold back. The engine does not burn oil and runs fine otherwise so I don’t think it is the torque converter. A friend of mine suggested I get the Speed Sensor checked, but I am not sure if that is the case

Any insight on this problem would be much appreciated

[jeffcoslacker]

That is interesting. I guess we can assume from the description that the problem does not lie in an engine control used during closed loop operation (warmed up), so that would rule out O2 sensors, EGR and TCC operation. It is normal for oil pressure to be high on start-up and drop as the oil warms. Does it do this repeatedly each time you drive it until warmed up, or just once and then it is fine?

[dlboivin]

Originally Posted by jeffcoslacker

That is interesting. I guess we can assume from the description that the problem does not lie in an engine control used during closed loop operation (warmed up), so that would rule out O2 sensors, EGR and TCC operation. It is normal for oil pressure to be high on start-up and drop as the oil warms. Does it do this repeatedly each time you drive it until warmed up, or just once and then it is fine?

Thanks for replying

It does it consistently and repeadtedly each time I drive until it is warmed up. I don't experience any difficulty if I immediately go to high speeds, on the highway for example. A friend suggested I use a transmission oil treatment?

Any thoughts?

Many thanks

[jeffcoslacker]

It is not slipping out of gear and overrevving, correct? Just bogs or stumbles? Can we assume fuel filter is good, just to rule it out?

[richtazz]

Check the IAC valve, as it may be sticking in it's bore. Since it only happens when the engine is cold, the IAC works similar to a choke in a carb and will cause a cold stumble on acceleration until the engine warms up. The IAC still functions when the engine is warm, but not as critically.

[decausby]

I am having the same problem with my 97 Lumina except it is an intermittant problem and seems to happen at different times. I have replaced the following: Spark plugs
Wires
Fuel Filter
Throttle position sensor
and am currently considering the fuel pump, but am unsure as this a high cost item